Proper tooth brushing technique, including length and coverage of brushing, helps ensure long-term dental health. Many dental problems are experienced by individuals who either don't regularly brush their teeth or who do so inadequately. Among individuals who do regularly brush, improper brushing habits can result in poor coverage of brushing and thus surfaces that are not adequately cleaned.
To facilitate proper brushing technique, toothbrushes have been designed to provide a timer function such that a user knows to brush for a minimum recommended amount of time. The timer function can include an audible sound, haptic feedback, or other notification mechanism to let the user know when a predetermined amount of time has elapsed. This provides the user with an indication that they have brushed their teeth for an adequate amount of time.
Another mechanism to facilitate proper brushing technique is to ensure that there is adequate cleaning of all dental surfaces, including areas of the mouth that are hard to reach or that tend to be improperly cleaned during an average brushing session. One way to ensure adequate coverage is to track the position of the toothbrush in the mouth during a brushing session and compare that to a map of the dental surfaces. For example, a system with sensors positioned in fixed relationship to the teeth of the user could track the movement of a toothbrush over the user's teeth.
Alternatively, the toothbrush could include one or more internal sensors that attempt to track movement of the device within the mouth. In such a system, the user starts with the toothbrush at a known, fixed position within the mouth and subsequent movement of the brush is determined from the one or more internal sensors. However, this approach has several limitations. Users are unable to move their head during brushing as this interferes with the proper positioning of the original fixed reference spot. The system is confused between certain regions of the mouth where data will be similar, such as the upper left inside of the mouth and the upper right outside of the mouth. The resolution of the system is low, meaning that only broad sections of the mouth can be tracked rather than more exact positioning such as teeth.
Accordingly, there is a continued need in the art for a method of tracking the movement of a toothbrush within the mouth using spatial sensor input without requiring exact starting position information.